import numpy as np
import pandas as pd
arr = np.arange(1,10).reshape(3,3)
df1 = pd.DataFrame(arr,columns=['a','b','c'])
df1.insert(0,'key',['001','003','002'])
print('',df1)
arr2 = np.arange(10,14).reshape(2,2)
df2 = pd.DataFrame(arr2,columns=['a','e'])
df2.insert(0,'key',['001','004'])
print('',df2)
df3 = pd.merge(df1,df2,how='left')
print('',df3)
df4 = pd.merge(df1,df2,how='left',on='key')
print('',df4)
df5 = pd.merge(df1,df2,how='right',on='key')
print('',df5)
df6 = pd.merge(df1,df2,how='inner',on='key',suffixes=('_1','_r'))
print('',df6)
df7 = pd.merge(df1,df2,how='outer',on='key',sort=True)
print('',df7)